Air intake system for off-road vehicle

ABSTRACT

An off-road vehicle includes a frame and four wheels that support the frame. Two seat assemblies are disposed side by side on the frame. The seat assemblies are separated from each other to define a space therebetween. An engine powers the wheels. The engine defines an air intake port that communicates with a combustion chamber. An air intake system delivers air to the intake port. At least a portion of the air intake system extends through the space.

PRIORITY INFORMATION

The present application is based on and claims the benefit of U.S.application Ser. No. 10/790,932, filed on Mar. 2, 2004; U.S. ProvisionalApplication No. 60/460,068, filed on Apr. 2, 2003; and U.S. ProvisionalApplication No. 60/459,958, filed on Apr. 2, 2003, pursuant to 35 U.S.C.§119(e).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an air intake system for anoff-road vehicle, and more particularly to an improved air intake systemfor an off-road vehicle that has at least two seat assemblies.

2. Description of Related Art

Off-road vehicles are designed to be operated over rugged terrain. Thesevehicles are often operated off-road over terrain such as, for example,steep inclines and declines, rough roads, and areas covered in mud andwater.

Off-road vehicles typically include a frame that is supported by wheels.In one common arrangement, the vehicle has four wheels, i.e., a pair offront wheels and a pair of rear wheels. An internal combustion engine isemployed to power at least the rear or front wheels, and most commonly,all of the wheels. Typically, the engine is combined with a transmissionto form an engine unit. The transmission transfers power to an outputshaft from a crankshaft of the engine. The output shaft drives thewheels. For example, Japanese Utility Model Publication JP-Y2-H6-34213discloses such an arrangement.

SUMMARY OF THE INVENTION

The engine has an air intake port communicating with a combustionchamber. An air intake system can be connected to the intake port todeliver air to the combustion chamber. The intake system can includecomponents such as, for example, a throttle body and an air intake duct.Those components need sufficient protection.

Due to the typical environment in which off-road vehicles operate, theintake systems of the off-road vehicles are likely to be hit by rocks,wooden blocks or the like or to ingest water. The intake systems of theoff-road vehicles, thus, require more protection than other types ofvehicles.

A need therefore exists for an improved off-road vehicle that cansubstantially protect an air intake system of the vehicle.

One aspect of an embodiment of the present invention involves anoff-road vehicle comprising a frame. A plurality of wheels supports theframe. At least two seat assemblies are disposed side by side on theframe. The seat assemblies are spaced apart from each other to define aspace therebetween. An internal combustion engine powers the wheels. Theengine comprises an air intake port. The air intake port is in directcommunication with a combustion chamber. An air intake system deliversair to the intake port. At least a portion of the air intake systemextends through the space.

In accordance with another aspect of an embodiment of the presentinvention, an off-road vehicle comprises a frame. A plurality of wheelssupports the frame. At least two seat assemblies are disposed side byside on the frame. The seat assemblies are spaced apart from each otherto define a space therebetween. An internal combustion engine powers atleast one of the plurality of wheels. The engine comprises an air intakeport and a combustion chamber. The air intake port communicates with acombustion chamber. The engine has a surface disposed within the spaceand the air intake port is at least partially positioned on the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features, aspects and advantages of the presentinvention are described in detail below with reference to the drawingsof a preferred embodiment, which is intended to illustrate and not tolimit the invention. The drawings comprise six figures in which:

FIG. 1 is a side elevational view of an off-road vehicle configured inaccordance with a preferred embodiment of the present invention;

FIG. 2 is a top plan view of the off-road vehicle of FIG. 1;

FIG. 3 is a side elevational view of an engine unit of the off-roadvehicle;

FIG. 4 is a side elevational view of a front differential and a portionof a steering mechanism of the off-road vehicle;

FIG. 5 is a partial sectional view taken along the line 5-5 of FIG. 2;and

FIG. 6 is a partial sectional view taken along the line 6-6 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1-7, an off-road vehicle, and particularly anair intake system for the off-road vehicle is described. While theintake system is described in connection with this particular type ofvehicle, those of skill in the art will appreciate that certainfeatures, aspects, and advantages of the present invention may haveutility in a wide range of applications for other vehicles. Forinstance, certain features, aspects and advantages of the presentinvention can be used with snow vehicles, tractors, utility vehicles,and the like.

With reference to FIGS. 1, 2 and 5, the off-road vehicle 30 preferablyhas an open tubular-type frame 32. The illustrated frame 32 comprises amain frame section 34, a front frame section 36, a rear frame section 38and a compartment frame section (or pillar frame section) 40.

The main frame section 34 includes a pair of side frame units 42 spacedapart side by side with each other. Each side frame unit 42 comprises afront tubular member 42 a and a rear tubular member 42 b. Each tubularmember 42 a, 42 b preferably is rectangular in section but otherconfigurations can be used. In one variation, the front and rear members42 a, 42 b can have a circular shape in section. Moreover, the members42 a, 42 b can have an incomplete tubular shape such as, for example, aU-shape. A rear end of the front tubular member 42 a is bent outwardlyand is coupled with a mid portion of the rear tubular member 42 b. Aforward end of the rear tubular member 42 b is bent inwardly and iscoupled with a mid portion of the front tubular member 42 a. Thus, inthe illustrated arrangement, both of the front and rear tubular members42 a, 42 b are nested together. The side frame units 42 preferably areconnected by front, center and rear cross members 44 (FIG. 2) thattransversely extend between the tubular members 42 a, 42 b.

The front frame section 36 extends generally upward from a front portionof the main frame section 34. The rear frame section 38 also extendsgenerally upward from a rear portion of the main frame section 34. Therear frame section 38 preferably includes a pair of rear frame members46. Several struts connect the rear frame members 46 to the side members42 of the main frame section 34 and support the rear frame members 46above the side members 42.

The compartment frame section 40 is disposed generally between the frontand rear frame sections 36, 38 in a side view as shown in FIG. 1. Thecompartment frame section 40 includes a pair of compartment members 48extending compartment members 48 are spaced apart from each other onboth sides of the off-road vehicle 30 to be placed more outward than themain frame section 34 in the illustrated embodiment.

A floorboard or floor panel 50 extends in an area generally defined bythe compartment members 48 in the top plan view (FIG. 2) and is affixedat least to the main frame 34. The floorboard 50 defines a passengercompartment together with the compartment frame section 40. As bestshown in FIG. 5, the illustrated floorboard 50 generally is a flat panelwith a portion that projects upward. That is, the floorboard 50comprises a horizontal section 51 defining a generally flat area and aprojection 52 defining a tunnel extending along a longitudinal centerplane LC (FIG. 2) of the frame 32 that extends vertically and fore toaft. The horizontal section 51 can support feet of a driver and apassenger and also can be used as a step when the driver or thepassenger enters or leaves the passenger area of the off-road vehicle30. The illustrated projection 52 is configured as a trapezoid insection and thus has slanted side surfaces 53 and a top surface 54.Other configurations also can be used.

The main, front, rear and compartment frame sections 34, 36, 38, 40preferably are welded to each other. The illustrated structure andarrangement of the frame 32, and the combination of the frame 32 and thefloorboard 50 are merely one example. Various structures, arrangementsand combinations other than those are practicable. For instance, therespective frame sections 34, 36, 38, 40 can be provided with struts orreinforcement members that are not described above.

With reference to FIGS. 1 and 2, the off-road vehicle 30 preferably hasa pair of front wheels 56 and a pair of rear wheels 58 both supportingthe frame 32. Each wheel 56, 58 preferably has a tire that is sized andconfigured to advantageously proceed over rough roads and in mud andwater. Relative to most similar conventional off-road vehicles, the tirecan have a higher internal pressure and/or can be equipped with an innertube, if desired. In some embodiments, a tubeless tire, which isrelatively wide and which has a relatively low air pressure, can beused. In one arrangement, the selected tires are sized as follows:25×8-12 at the front end and 25×10-12 at the rear end.

The front and rear wheels 56, 58 preferably are coupled with the frame32 through a front suspension mechanism 60 and a rear suspensionmechanism 62, respectively. The front suspension mechanism 60 swingably(up and down) and independently suspends both the front wheels 56. Therear suspension mechanism 62 also swingably (up and down) andindependently suspends both the rear wheels 58. Thus, the illustratedoff-road vehicle 30 preferably features four wheel independentsuspension.

With reference to FIGS. 1-3, the off-road vehicle 30 preferably has aseat unit 66. The illustrated seat unit 66 comprises a pair of seats orseat sections 68 such that the driver and the passenger can sit side byside. In some arrangements, the seat unit 66 can comprise a bench style,or split bench style, seat. In such arrangements, two or more seatingpositions are positioned laterally across the vehicle.

In the illustrated arrangements, a pair of separate seat sections 68 areprovided. The rear frame section 38, at least in part, forms a pair ofseat pedestals (not shown). Each seat 68 and each seat pedestal togetherform a seat assembly. The illustrated off-road vehicle 30 thus has twosets of seat assemblies. The seat assemblies are spaced apart from eachother to form a space 70 (FIG. 2) therebetween.

A preferable construction or structure of an off-road vehicle similar tothe off-road vehicle 30 is disclosed in, for example, a co-pending U.S.application Ser. No. 10/119,439 titled “ENGINE ARRANGEMENT FOR OFF-ROADVEHICLE,” having a co-pending U.S. application Ser. No. 10/791,111,titled “OFF-ROAD VEHICLE WITH TRANSMISSION,” having U.S. applicationSer. No. 12/116,118, titled “FLOOR ARRANGEMENT FOR OFF-ROAD VEHICLE,”having a co-pending U.S. application Ser. No. 10/790,932, titled“STEERING SYSTEM FOR OFF-ROAD VEHICLE,” having a co-pending U.S.application Ser. No. 10/791,164, titled “OFF-ROAD VEHICLE WITH AIRINTAKE SYSTEM,” having a co-pending U.S. application Ser. No.11/775,772, titled “OFF-ROAD VEHICLE WITH WHEEL SUSPENSION,” having aco-pending U.S. application Ser. No. 10/792,463, titled “FRAMEARRANGEMENT FOR OFF-ROAD VEHICLE,” having and a co-pending U.S.application Ser. No. 12/116,118, titled “TRANSMISSION FOR OFF-ROADVEHICLE,” having the entire contents of which are hereby expresslyincorporated by reference.

In this description, the terms “front” and “forward” mean the directionin which the driver or passenger looks straight when seated on the seats68. Also, the terms “rear,” “rearward” and “backward” mean the directionopposite to the front direction.

Each seat 68 preferably comprises a seat cushion 72 and a seat back 74.The seat cushion 72 extends generally horizontally over the seatpedestal and is detachably or removably affixed to the seat pedestal.The seat back 74 extends generally vertically and upward from a rearportion of the seat cushion 72. In the illustrated arrangement, the seatcushion 72 and the seat back 74 are formed unitarily. In one variation,the seat cushion 72 and the seat back 74 can be separately formed andassembled together.

With reference to FIG. 3, the illustrated seat unit 66 has a forward end78, a rear end 80 and a top end 82. In this arrangement, the forward end78 of the seat unit 66 is defined by forward ends of the seat cushions72. If, however, the seat pedestals extend forward of the seat cushions72, forward ends of the seat pedestals can define the forward end of theseat unit 66. An imaginary forward, generally vertical plane 84 can bedefined through the forward end of the seat unit 68.

The rear end 80 and the top end 82 preferably are defined by rear endsof the seat backs 74 and top ends of the seat backs 74, respectively. Animaginary rearward, generally vertical plane 86 can be defined throughthe rear ends of the seat backs 74. Also, an imaginary, generallyhorizontal plane 88 can be defined through the top ends 82 of the seatbacks 74. The seat 68, however, can be shaped in various configurations.The seat back may be omitted under some circumstances. If the seat back74 is omitted, the imaginary rear, generally vertical plane 86 can bedefined more forwardly as indicated by the reference numeral 86A.Furthermore, the rear, generally vertical plane 86 may be defined moreforwardly as indicated by the reference numeral 86B if the thickness ofthe seat back 74 is reduced. Also, the generally horizontal plane 88 maybe shifted downward to a top surface 82A of each of the seat cushions 72as indicated by the reference numeral 88A.

Thus, the forward, rear and top ends 78, 86, 82, the imaginary forwardand rear generally vertical planes 84, 86 and the imaginary generallyhorizontal plane 88 are normally determined depending on a configurationof the seat assembly, which includes the seat 68 and the seat pedestalin the illustrated arrangement. More practically, the rear end 86 shouldbe substantially on the imaginary, generally vertical forward plane 86Aor the imaginary, generally vertical rear plane 86B. Also, the top end82 should be substantially the top surface 82A of the seat cushions 72and should be on the imaginary, generally horizontal plane 88A.

Because the seats 68 are positioned on the seat pedestals, which have acertain height, a relatively large space is formed below the imaginaryhorizontal plane 88A. Additionally, the seat unit 66 can have any numberof seats, such as, for example, three seats in some alternativearrangements.

With reference to FIGS. 1, 2 and 6, the off-road vehicle 30 preferablyhas a carrier or cargo box 92 behind the seat unit 66. The illustratedcarrier 92 extends over a rear portion of the rear frame section 38 andis suitably affixed at least to the rear frame members 46. In onearrangement, the carrier 92 can be tipped rearward to allow its contentsto be dumped. The carrier 92 preferably is formed generally in the shapeof a rectangular parallelepiped and has a bottom, a front, a rear and apair of lateral sides. That is, the carrier 92 is generally configuredas an open-topped box.

As best shown in FIG. 6, the bottom of the carrier 92 preferablycomprises steps 96 on both sides such that side portions 98 of thebottom are positioned higher than a central portion 100 of the bottom.The steps 96 advantageously reduce the likelihood that the rear wheels58 would contact carrier 92 when the rear wheels 58 are in an upper mostposition of suspension travel. It should be noted that the describedmovement of the rear wheels 58 is the relative movement thereof inrelation to the carrier 92. The center bottom portion 100 thus increasesthe capacity of the carrier 92. Each step 96 preferably extends fore toaft as shown in FIG. 2. Longitudinally shortened steps (similar to wheelwells) also can be used.

The center bottom portion 100 helps lower the center of gravity of thecarrier 92. The illustrated off-road vehicle 30 thus features enhancedstability. The steps 96 also reduce lateral movement of loads.Manufacture of the carrier 92 is simple and cost effective because thesteps 96 only extend fore to aft. In addition, the steps 96 may increasethe stiffness of the carrier 92.

With reference to FIGS. 1, 2 and 4, the off-road vehicle 30 comprises asteering mechanism 104. The steering mechanism 104 in the illustratedarrangement includes a steering wheel 106. The steering wheel 106 isaffixed to the frame 32 for steering movement in front of the seat 68for the driver, which is located on the left-handed side of theillustrated off-road vehicle 30.

The illustrated steering mechanism 104 preferably comprises a steeringshaft unit 110 coupled with the steering wheel 106, a tie-rod (notshown) coupled with the front wheels 56, and a rack-and-pinion assembly112 (FIG. 4) that connects the steering shaft unit 110 to the tie-rod.The rack-and-pinion assembly 112 converts the pivotal movement of thesteering wheel 106 to an axial movement of the tie-rod. The rack-andpinion assembly 112 preferably is housed in a gear case 114.

The steering wheel 106 can be rotated clockwise and counterclockwise toeffect turning movement of the steerable wheels. In some arrangements, acontrol stick can be used in place of a steering wheel 106. Othersuitable directional control devices also can be used, such as, withoutlimitation, handlebars, push-buttons, foot pedals and the like.

As best shown in FIG. 2, the illustrated steering shaft unit 110comprises an upper steering shaft 116 and a lower steering shaft 118both pivotally affixed to the frame 32. The upper shaft 116 extendsupward and rearward toward the driver's area and the steering wheel 106is affixed to the top end of the upper shaft 116. The upper shaft 116preferably extends generally parallel to the longitudinal center planeLC. The lower shaft 118 extends toward the longitudinal center plane LC(i.e., toward a laterally central area of the vehicle) from a lower endof the upper shaft 116 through a universal joint (not shown) and iscoupled with the rack-and-pinion assembly 112, which is mounted withinthe case 114.

The tie rods preferably are connected to rod sections that extendoutward from the rack and pinion assembly 112. In some arrangements, aninner ball joint couples the rod sections to the respective tie rods.Also, an outer ball joint preferably couples each tie rod to a knucklearm (not shown) that is associated with each front wheel 56. Eachknuckle arm is coupled with a king pin (not shown) that extends from anaxle of the front wheel 56. The tie-rods move axially along with the rodsections when the steering shaft 110 is rotated.

As described above, the vehicle 30 preferably includes four wheelindependent suspension. In such arrangements, as discussed above, theouter ball joints can move around on an imaginary sphere that is definedabout the inner ball joint. In other words, the outer ball joint canmove transversely as well as around the surface of the imaginary sphere.The knuckle are is only capable of moving along an arc defined by thesuspension link connecting the wheel to the frame. The knuckle arm,thus, rotates about the king pin and causes bump steering unless thecurve defined by the suspension link is consistent with the spheredefined about the inner ball joint. In addition, bump steering causeschanges in the toe angle of the front wheels.

To reduce bump steering, as shown in FIG. 4, the gear case 114preferably is mounted on a front differential housing 122. The frontdifferential housing 122 advantageously is positioned on thelongitudinal center plane LC of the frame 32. The front differentialhousing 122 also preferably is disposed between the front tubularmembers 42 a at a location just rearward of a forwardmost cross member44 in the illustrated arrangement. In one arrangement, the gear case 114can be unitarily formed with the differential housing 122. The frontdifferential housing 122 incorporates a front differential gear unit 124and is relatively stiff. The gear case 114 preferably has a bracket 126extending downward and the differential housing 122 comprises a mountsurface 128. The bracket 126 is affixed to the mount surface 128 bybolts 130 or other suitable mounting techniques.

Preferably, the mount surface 128 is a top surface of the housing 122.That is, a bottom surface of the illustrated gear case 114 can besecured to the top surface of the housing 122. Accordingly, sufficientclearance can be provided adjacent another surface of the gear case 114to enable the lower steering shaft 118 to be coupled to therack-and-pinion assembly 112. The illustrated arrangement alsoadvantageously enables the steering shaft 110 to be shortened, whichdecreases its weight, because the surface adjacent to the couplingregion is closer to the top surface 128 of the housing 122. Moreover,the tie-rods are positioned in the illustrated arrangement in a mannerthat reduces the likelihood that they will interfere with the shafts ofthe front differential 124, which are described in greater detail below.

Because the front differential housing 122 and the gear case 114 aresecured together at a location along the longitudinal center plane LC,the tie-rods can be elongated relative to a construction in which thegear case 114 is mounted off-center with respect to the longitudinalcenter plane LC. Further, the tie-rods can have substantially equallengths to each other while also being elongated in the illustratedarrangement. The elongation of the tie rods results in an increaseddiameter or circumference of the imaginary spherical surface. Theenlarged imaginary spherical surface greatly increases the availablesuspension designs with which bump steering can be reduced. Moreover,the illustrated arrangement greatly decreases the toe angle changes ofthe right and left front wheels 56 caused by movements controlled by thesuspension system. Accordingly, greater design freedom is provided whilesimultaneously reducing bump steering. Furthermore, no special bracketsor stays are used to mount the rack and pinion arrangement (e.g., thegear case 114) and the gear case 114 can be securely mounted to theframe 32 through the front differential housing 122. During assembly ofthe vehicle, the gear case 114 can be affixed to the front differentialhousing 122 before the housing 122 is affixed to the frame 32 whicheases assembly because the connection of the front differential housing122 and the gear case 144 can occur outside of the cramped space withinthe vehicle.

Also, the mounting arrangement only requires the mount surface 128 to beformed on the differential housing 122, because the gear case 114 canhave the bracket 126 regardless whether the gear case 114 is affixed tothe differential housing 122 or not.

With reference to FIGS. 1 and 2, a hood or bonnet 134 surrounds at leasta front portion of the main frame section 34, the front frame section36, the front wheels 56 and a major portion of the steering mechanism104. A dashboard 136 preferably depends from a rear portion of the hood134. The dashboard 136 faces toward the passenger compartment and ameter unit 138 preferably is disposed in a central portion of thedashboard 136. The meter unit 138 preferably incorporates meters and/orgauges such as, for example, a speedometer, a fuel level meter, and thelike. Because of this meter unit arrangement, the driver can easily viewthe individual meters at a glance.

With reference to FIGS. 1-5, the off-road vehicle 30 has a prime moverthat powers the off-road vehicle 30 and particularly the front and rearwheels 56, 58. The prime mover preferably is an internal combustionengine 142. Alternatively, an electric motor can replace the engine 142.Engine power is transferred to the front and rear wheels 56, 58 througha suitable transmission 144 and a suitable drive mechanism 146. In theillustrated arrangement, the engine 142 and the transmission 144 arecoupled together to form an engine unit 148. The illustratedtransmission 144 advantageously includes an endless V-belt transmissionmechanism and a switchover mechanism. The illustrated drive mechanism146 comprises a forward driveshaft 150 extending forward from the engineunit 148, a rear driveshaft 152 extending rearward from the engine unit148, the front differential 124 is coupled with the front axles (notshown) of the front wheels 56, and a rear differential 154 is coupledwith the rear axles (not shown) of the rear wheels 58. In somearrangements, a single axle can replace the half axles.

As shown in FIGS. 1-3, the engine unit 148 preferably is positionedgenerally lower than the imaginary, generally horizontal plane 88 andgenerally in the space 70 defined between the seat assemblies. Theillustrated engine 142 operates on a four-stroke combustion principle,however, other engine operating principles also can be used. The engine142 preferably has a single cylinder block 158 that extends generallyupward and rearward from a lower section of the engine unit 148. Thatis, the cylinder block 158 has a cylinder axis CA that inclines relativeto vertical at a certain angle. The illustrated cylinder axis CAinclines from vertical at approximately 45 degrees.

In the illustrated arrangement, the engine 142 is an internal combustionengine. As such, the cylinder block 158 preferably defines a cylinderbore (not shown) therein. A piston (not shown) is reciprocally disposedwithin the cylinder bore (not shown). A cylinder head 160 preferablycloses an upper end of the cylinder bore to define, together with thecylinder bore and the piston, a combustion chamber 163.

The cylinder head 160 also defines a pair of intake ports 162 and a pairof exhaust ports 166 that communicate with the combustion chamber 163.An intake valve can be provided at each intake port 162 to selectivelyopen the combustion chamber 163 to an air intake system 164. In theillustrated arrangement, the air intake system 164 is coupled with theintake ports 162 at a front surface 165 of the cylinder head 160. Thefront surface 165 of the cylinder head 160 preferably is disposedsubstantially within the space 70 and preferably faces generally forwardand upward. With reference to FIG. 2, the front surface 165 desirably isdisposed generally between the seats 68.

The air intake system 164 introduces air into the combustion chamber 163through the intake ports 162 when the intake valves (not shown) open thepassage into the combustion chamber 163. An exhaust valve (not shown)also is provided at each exhaust port 166 to selectively open thecombustion chamber 163 to an exhaust system 168. In the illustratedarrangement, the exhaust system 168 is coupled with the exhaust ports166 at a rear surface 169 of the cylinder head 160. The rear surface 169of the cylinder head 160 is positioned substantially opposite to thefront surface 165 and generally faces rearward and downward. The exhaustsystem 168 routes exhaust gases from the combustion chamber 163 to anoutside location.

A cylinder head cover 170 is attached to the cylinder head 160 toenclose one or more camshafts (not shown). The camshafts (not shown)preferably are journaled on the cylinder head 160. The camshafts (notshown) actuate the intake and exhaust valves at speeds that aregenerally in proportion to the engine speed. Other suitable methods ofactuating the valves also can be used.

An upper section of the illustrated engine unit 148 includes thecylinder block 158, the cylinder head 160 and the cylinder head cover170. The upper section at least in part extends rearwardly beyond theimaginary rear, generally vertical plane 86 (and 86A or 86B).

A lower section of the engine unit 148, which is the balance of theengine unit 148, comprises a crankcase 174, which closes a lower end ofthe cylinder bore (not shown). A crankshaft 176 preferably is journaledwithin the crankcase 174 and is coupled with the piston (not shown) inany suitable manner. In the illustrated arrangement, the crankshaft 176extends generally transverse to a direction of travel of the vehicle butother orientations also can be used. The reciprocal movement of thepiston results in rotation of the crankshaft 176. The crankshaft 176preferably drives the camshafts via a camshaft drive mechanism.

The crankcase 174 also houses an input shaft for a shiftable portion ofthe transmission 144. The input shaft is positioned forward of thecrankshaft 176. The lower section of the engine unit 148 also comprisesa V-belt housing 178, which is positioned next to the crankcase 174 inthe illustrated arrangement. Moreover, in the illustrated arrangement,the V-belt housing 178 is defined on the left-hand side of the crankcase174. The V-belt housing 178 houses the V-belt transmission mechanism(e.g., continuously variable transmission). Thus, the lower section ofthe engine unit 148 (which comprises at least the crankcase 174 and theV-belt housing 178) also defines, at least in part, a transmissionhousing 180. The transmission 144 will be described in greater detailbelow.

With reference to FIGS. 1-3 and 5, the illustrated air intake system 164extends forward to a location under the hood 134 from the intake ports162 of the engine 142. The intake system 164 preferably comprises athrottle body or carburetor 182, an accumulator or plenum chamber 184,an air intake duct 186 and an air cleaner unit 188.

With reference to FIG. 3, the throttle body 182 is connected to theintake ports 162 through an air intake conduit 192. The throttle body182 comprises a throttle valve 194 that regulates a rate of airflowamount delivered to the combustion chamber 163. The throttle valve 194preferably is a butterfly valve and generally is journaled for pivotalmovement. The level of airflow depends on an angular position of thethrottle valve 194—when the throttle valve is closed or substantiallyclosed, minimal air flow results, while when the throttle valve isopened or substantially opened, maximum air flow results.

An accelerator pedal or control member 196 (FIG. 5) preferably isdisposed at a front end of the floorboard 50 for pivotal movement tocontrol the position of the throttle valve 194. A throttle cableconnects the accelerator pedal 196 to the throttle valve 194. The driverthus can control the throttle valve 194 by adjusting an angular positionof the accelerator pedal 196 with a foot 198. Normally, the greater thethrottle valve 194 opens, the higher the rate of airflow amount and thehigher the engine speed. Other suitable mechanisms and/or electricalconnections also can be used to transmit operator demand to the throttlevalve or engine.

With reference to FIG. 5, the heel (i.e., lower portion of the foot 198)of the driver can lean against the slanted side surface 53 on theleft-hand side of the projection 52 when the foot 198 is in position tooperate the accelerator pedal 196 because the slanted side surface 53 islocated generally adjacent to the accelerator pedal 196. In other words,the slanted portion 53 functions as a foot brace and reduces thelikelihood that the operator's foot 198 will slide off of theaccelerator pedal 196 when the off-road vehicle 30 is operated overrough terrain or when the off-road vehicle 30 turns a sharp corner at arelatively high speed, which increases the centrifugal forcestransmitted to the foot 198. Thus, the illustrated construction canprovide the driver with better body control and improved driving bodyposition. Similarly, the slanted side surface 53 on the right-hand sidealso can function as the foot brace. Thus, the passenger, or driver insome configurations, can also have a foot brace for use during operationof the vehicle.

With reference again to FIG. 3, the throttle body (e.g., the carburetor)182, which functions as a charge former, preferably also has a fuelmeasurement mechanism that measures an amount of fuel mixed with the airin accordance with the rate of airflow. Because of this fuel measurementmechanism, the air/fuel ratio supplied to the engine can be controlledand/or optimized depending upon engine operating conditions. The fuel isdelivered to the throttle body 182 from a fuel tank (not shown) that canbe suitably mounted and suitably positioned on the frame 32.

Other charge formers such as, for example, a fuel injection system canbe used. The fuel injection system has a fuel injector that isconfigured to spray fuel directly into the combustion chamber 163 orinto a portion of the air intake system downstream of the throttlevalve. An engine control unit (ECU) can control the amount of fuelinjected, for example, in accordance with the airflow rate.

With reference to FIGS. 1 and 2, the accumulator 184 can be coupled withan inlet of the throttle body 182. The accumulator 184 generally forms aportion of the intake duct 186 in the broad sense of the term butprovides a larger volume or cross-sectional area as compared to thebalance of the intake duct 186. Such a construction allows air toaccumulate prior to delivery to the throttle body 182. As best shown inFIG. 1, the accumulator 184 is generally shaped as an arcuateconfiguration. Such a construction advantageously smoothens the deliveryof air to the engine. Furthermore, because the accumulator 184 has arelatively large volume and is disposed next to the throttle body 182,the intake efficiency of the induction system is greatly improved. Thatis, sufficient air can be quickly supplied to the engine 142 even whenthe engine is being operated at a relatively high engine speed. This isadvantageous due to the longer length of the intake duct 186.

In the illustrated arrangement, the air intake conduit 192, the throttlebody 182 and the accumulator 184 together extend forwardly of the enginewithin a region defined between the seats 68. Upper portions of thethrottle body 182 and the accumulator 184 preferably are positionedslightly higher than the top ends 82A of the seat cushions 72. Aforward-most portion of the accumulator 184 turns downward at or justforward of the forward end of the seat assemblies.

Because of this arrangement, the throttle body 182 and at least aportion of the accumulator 184 are interposed between the seatassemblies and are positioned within, or just adjacent to, the space 70.Thus, the throttle body 182 and the accumulator 184 are positionedwithin a protective region of the vehicle that is located higher than alowermost surface of the frame assembly or the floorboard 50. Suchpositioning reduces the likelihood that dirt and other road debris thatmay be kicked up underneath the vehicle will damage the throttle body182 or the accumulator 184. Such placement also facilitates servicing ofthese components and protects these components from water damage whilefording a stream, a mud bog or the like.

The illustrated accumulator 184, which is positioned within the mostdownstream portion of the illustrated intake duct 186, ends above alowermost surface defined by the rear frame section 38. The balance ofthe air intake duct 186, which has a smaller volume or cross-sectionalarea than the accumulator 184, preferably comprises a downstream section200, a middle section 202 and an upstream section 204, which are providea contiguous air flow path in the illustrated embodiment. The downstreamsection 200 extends downwardly from the accumulator 184 to a lowermostportion of the rear frame section 38. The middle section 202 extendsforwardly in a generally horizontal direction from a lower end of thedownstream section 200.

With reference to FIG. 5, in the illustrated arrangement, the middlesection 202 extends through a tunnel defined by the projection 52 of thefloorboard 50. Because of this arrangement, the middle section 202advantageously is positioned higher than the horizontal section 51 ofthe floorboard 50, which greatly reduces the likelihood of damage fromrocks, sticks, road debris or the like. Furthermore, the driver and/orthe passenger are able to maintain a good riding body position becausethe horizontal section 51 is positioned generally vertically lower thanthe middle section 202. Moreover, the illustrated arrangementcontributes to a lower center of gravity for the off-road vehicle 30because the height of the seats 68 does not need to be increased toaccommodate the middle section 202 or another portion of the airinduction system.

The middle section 202 preferably ends at a location close to the frontframe section 36. The upstream section 204 extends generally verticallyupward from the middle section 202. In addition, the upstream section204 preferably is positioned within a space defined below the hood 134.To increase the protection from ingestion of water, the forwardmostportion of the upstream section 204 extends forward and slightlydownward along a lower surface of the hood 134.

The air cleaner unit 188 preferably is attached at an upstream end ofthe intake duct 186 and extends generally along the lower surface of thehood 134. The illustrated air cleaner unit 188 has a relatively largevolume and has a cleaner element therein. The air cleaner unit 188 alsohas an air inlet port. Ambient air is drawn into the air cleaner unit188 through the air inlet port and passes through the filtration elementsuch that foreign substances such as, for example, dust, mud or watercan be substantially removed from the air that is being introduced intothe engine.

The air, which has been cleaned in the cleaner unit 188, flows to theaccumulator 184 through the intake duct 186. The airflow amount isregulated by the throttle valve 194 in the throttle body 182.Simultaneously, an amount of fuel is measured by the fuel amountmeasurement mechanism in the throttle body 182 in response to the airamount. An air/fuel charge that has a proper air/fuel ratio is formedand is delivered to the combustion chamber 163 when the intake valvesopen the intake ports 162. The air/fuel charge is ignited by an ignitionsystem (not shown) and burns within the combustion chamber 163. Theburning of the charge causes expansion of the gases and increasedpressure that results in movement of the piston. The crankshaft 176 isrotated within the crankcase 174 by the movement of the piston.

With reference to FIGS. 1-3, the burnt charge, i.e., exhaust gases, aredischarged through the exhaust system 168. The illustrated exhaustsystem 168 preferably comprises a pair of exhaust conduits 208 and amuffler 210. The exhaust conduits 208 are coupled with the respectiveexhaust ports 166 and extend generally rearward. The exhaust conduits208 extend generally parallel to each other. Preferably, the exhaustconduits 208 have a wavy shape that serpentines up and down, as shown inFIGS. 1 and 2. Rearward ends of the exhaust conduits 208 preferablyextend beyond a rear end of the rear frame section 38. The muffler 210is coupled with the rear ends of the exhaust conduits 208.

The muffler 210 preferably has a cylindrical shape. A center axis of themuffler 210 preferably extends in a generally transverse directionrelative to the longitudinal center plane LC of the frame 32. Themuffler 210 has a relatively large volume to reduce exhaust energy andnoise. An outlet port 212 can be formed at a side surface, which is on aleft-hand side in the illustrated embodiment. Other arrangements alsocan be used. The exhaust gases flow through the exhaust conduits 208 andare discharged through the outlet port 212 of the muffler 210.

The engine 142 can have systems, devices, components and members otherthan those described above. For example, the illustrated engine 142 canemploy a liquid cooling system that uses coolant (e.g., water), which iscirculated through a heat exchanger, to cool the engine 142.

With reference to FIGS. 1-3, the change speed mechanism and the V-belttransmission mechanism together have a common output shaft 216. Theoutput shaft 216 extends generally parallel to the crankshaft 176 at alocation in front of the crankshaft 176. The output shaft 216 preferablyextends through the crankcase 174 and the V-belt housing 178 and isjournaled for rotation relative to these components. Because of thisarrangement, the output shaft 216 is positioned at a location generallybetween the front wheels 56 and the crankshaft 176. In other words, thecrankshaft 176 is positioned between the output shaft 216 and the rearwheels 58.

The crankshaft 176 extends into the V-belt housing 178 and carries adrive pulley 218 (FIG. 3). The output shaft 216 carries a driven pulley220. The drive and driven pulleys 218, 220 both comprise an axiallyfixed pulley member and an axially movable pulley member that is movablealong the respective axis of the crankshaft 176 or the output shaft 216.Together, the pulley members form a V-shaped valley that expands andcontracts with changes in engine speed.

An endless belt 222 or chain, which belt has a V-configuration insection is wound around the drive pulley 218 and the driven pulley 220.Normally, the movable pulley member of the drive pulley 218 is urged tostay apart from the fixed pulley member by the bias force of a biasmember such as, for example, a spring. The movable pulley member of thedriven pulley 220 is urged to stay close to the fixed pulley member bythe bias force of a bias member such as, for example, a spring.

Each movable pulley member can move axially against the bias force by aclutch mechanism which is provided on either pulley 218, 220. The clutchmechanism acts by centrifugal force created when the crankshaft oroutput shaft turns at a speed higher than a preset speed. The change indiameter of one pulley causes a corresponding change in the otherpulley. Thus, both diameters of the drive pulley 218 and the drivenpulley 220 vary to automatically change the transmission ratio betweenthe drive pulley 218 and the driven pulley 220, normally in response tothe engine speed.

With reference to FIGS. 1-3, the V-belt housing 178 preferably has anair inlet port 226 at a rear end and an air outlet port 228 at a frontend. An air inlet duct 230 (FIGS. 1 and 2) preferably is coupled to theinlet port 226, while an air outlet duct 232 preferably is coupled tothe outlet port 228. The inlet duct 230 extends generally rearward andupward and generally behind the seat back 74 on the left-hand side. Theinlet duct 230 has an inlet opening 233 that opens forward and ispositioned higher than top surfaces of the seat cushions 72. The outletduct 232 extends generally upward and rearward and generally along abottom surface of the seat cushion 72 on the left-hand side. The outletduct 232 has an outlet opening 234 that opens generally rearward.

Cooling air is introduced into the V-belt housing 178 through the inletduct 230 and the air inlet port 226 when the crankshaft 176, the outputshaft 216 and the drive and driven pulleys 218, 220 rotate. In somearrangements, one or both of the pulleys can be provided with fan bladesto help induce higher speed air flow as the engine speed increases.Other embodiments can provide a ram air type of air flow. Havingcirculated with the belt chamber of the transmission, the air then isdischarged through the outlet port 228 and the outlet duct 232.

With reference to FIGS. 1-3, the engine output that has been transferredto the output shaft 216 through the V-belt mechanism is transferred tothe drive mechanism 146 through the change speed transmission mechanism.This mechanism preferably is configured to provide a parking state, ahigh speed forward state, a neutral state, a low speed forward state,and a reverse state. The mechanism preferably comprises a suitable geartrain that allows an operator to select among at least theabove-mentioned operating states. A bevel gear assembly 236 can becoupled with the mechanism.

The mechanism also comprises a shift lever unit 240 that extends fromthe crankcase 174. The shift lever unit 240 preferably is connected tothe rest of the switchover mechanism within the crankcase 174 through asuitable linkage (not shown). The shift lever unit 240 preferably isplaced generally within the space defined between the seats 68. Theillustrated lever unit 240 is positioned generally at the forward-mostportion of the space. Such placement facilitates ease of use.

The shift lever unit 240 preferably comprises a lever 244 and a levercover 246. The lever 244 preferably is affixed to the frame 32 directlyor indirectly for pivotal movement around a fulcrum. In one variation,the shift lever unit 240 can comprise a lever that moves axially. Thedriver thus can control the change speed mechanism in the crankcase 174and vary the transmission operating state among at least the parkingstate, the high speed forward state, the neutral state, the low speedforward state and the reverse state by operating the lever 244.

Because of the advantageous configuration of the drive train relative tothe shift lever unit 240, the shift lever unit 240 is positioned closeproximity to the change speed mechanism of the transmission 144. Thelinkage thus can be short enough to make the switchover mechanismcompact and also to improve the feeling that the driver might have whenoperating the shift lever unit 240.

With reference to FIGS. 1-4, the output of the switchover mechanism istransferred to the drive mechanism 146 through the bevel gear 236. Inthe illustrated arrangement, the bevel gear 236 is coupled with aforward intermediate shaft 248. The forward drive shaft 150 is pivotallycoupled to the forward intermediate shaft 248 through a universal joint250. That is, the universal joint 250 comprises a first yoke 252, asecond yoke 254 and a cross pin 256 pivotally coupling the first andsecond yokes 252, 254.

The forward driveshaft 150 is coupled with a front differential inputshaft 262 (FIG. 4) of the front differential 124. The front differentialhousing 122 preferably encloses at least a portion of the input shaft.The front differential input shaft is coupled with a mechanism of thefront differential 124, such as a pinion or differential gear. A pair ofoutput shafts 262 extends from the mechanism of the front differential124. Each output shaft 262 is connected to a respective one of the frontwheels 56.

Preferably, the gear case 114 of the rack-and-pinion assembly 112 ispositioned behind the output shafts 262. This arrangement advantageouslylocates the tie-rods and the knuckle arms of the steering system 104 ina space located behind linkages that connect the respective outputshafts 263 with the associated front wheels 56. Thus, the knuckle armscan have a sufficient length and bump steering can be reduced. Further,such a placement provides some degree of protection to these components.

With reference to FIG. 5, the forward driveshaft 150 extends forwardlywithin the tunnel defined by the projection 52 of the floorboard 50 andgenerally adjacent to the middle section 202 of the intake duct 186. Theforward driveshaft 150 thus is positioned higher than the horizontalsection 51 of the floorboard 50. Accordingly, the forward driveshaft 150is generally protected from significant impacts from rocks, sticks, roaddebris and the like. In some arrangements, at least a length of a loweropening of the tunnel can be closed with a protective plate or the liketo further protect both the driveshaft 150 and the middle section 202 ofthe intake duct 186.

In the illustrated arrangement, a rear intermediate shaft 258 also isconnected to the bevel gear 236 through a suitable connection. The reardriveshaft 152 is connected to the rear intermediate shaft 258 through aspline coupling 260. Other couplings or a unitary shaft can also beused. The rear driveshaft 152 is coupled with a rear differential inputshaft (not shown) of the rear differential 154. The rear differentialinput shaft preferably is coupled with the rear wheels 58 throughanother differential mechanism formed within the rear differential 154.

The off-road vehicle 30 preferably has other devices, components andmembers. For example, the differentials can be selectively lockable suchthat the differential function can be eliminated on demand. Moreover, abrake system can be provided to slow or stop rotation of the wheels 56,58 or another driveline component (e.g., the driveshafts). A brake pedal270 (FIG. 5) can be disposed next to the accelerator pedal 196 and canbe connected to brake units that are coupled with the wheels 56, 58. Insome arrangements, the brake units can comprise disk brakeconfigurations. The driver thus can stop the off-road vehicle 30 byoperating the brake pedal 270.

Various ducts, conduits, cables and the like other than the forwarddriveshaft 150 and the air intake duct 186, which are symbolicallyindicated by a reference numeral 274 of FIG. 5, also can extend throughthe tunnel defined by the projection 52 of the floorboard 50. Forexample, a brake cable and a coolant hose can pass therethrough. Thebrake cable could form a portion of the brake system and connects thebrake pedal and brake units disposed at the respective wheels 56, 58.The coolant hose could extend between the engine 142 and a radiator (notshown) that might be disposed under the hood 134 or in another suitablelocation. Because of this duct and conduit arrangement, those ducts,conduits and cables also can be placed higher than the horizontalsection 51 of the floorboard 50 and are well protected without impingingupon the driver and passenger seating areas and without substantiallyraising the center of gravity of the vehicle.

In one arrangement, the crankshaft 176 can be positioned beyond theimaginary rear vertical plane 86, 86A, 86B and the output shaft 216 canbe positioned between the forward vertical plane 84 and the rearvertical plane 86, 86A, 86B. In the illustrated arrangement, both theoutput shaft 216 and the crankshaft 176 are disposed between theimaginary forward generally vertical plane 84 and the imaginary reargenerally vertical plane 86. This is also true in the illustratedarrangement even if the imaginary rear vertical plane is defined by theplane 86B. A majority of the illustrated engine unit 148, thus, can belocated generally below the seat unit 66. Such an arrangement allows thewheelbase of the off-road vehicle 30 to be shortened in comparison withan arrangement in which a majority of the engine unit 148 is locatedbehind the seat unit 66. Accordingly, the illustrated off-road vehicle30 benefits from a substantially shortened wheel base which results inimproved maneuverability.

In the illustrated arrangement, a majority of the engine unit 148 alsois laterally positioned generally between the seats 68. However, in somearrangement, it may be advantageous to place a majority of the engineunit 148 under one of the seats 68. The illustrated engine unit 148 canbe accommodated in such a position because the cylinder block 158, thecylinder head 160 and the cylinder head cover 170 are inclined upward.Thus, they can be positioned behind the imaginary rear vertical plane86, 86A, 86B by slightly shifting the position of the crankshaft 176, orthe positions of the crankshaft 176 and the output shaft 216, rearward.In some arrangements, the engine 142 can be disposed generally on itsside such that the engine body extends generally horizontally withouthaving a significant portion extending upward.

In the illustrated arrangement, the engine 142 is located generallyrearward of the change speed mechanism including the output shaft 216.Moreover, the engine is positioned generally rearward of, and lowerthan, the seating area. Thus, heat generated by the engine 142 can besubstantially isolated from the driver and/or the passenger, andparticularly isolated from the feet of those persons both when seatingand when mounting or dismounting from the vehicle. The seat backs 74further insulate the driver and/or passenger from any heat that mayradiate from the engine or exhaust system. In addition, the cylinderblock 158, the cylinder head 160 and the cylinder head cover 170 in thisarrangement generally are directed rearward and are positioned generallyrearward of the occupants. Thus, it is very unlikely that the engineheat will affect the occupants of the vehicle.

The exhaust system 168 carries a great deal of heat as well while theintake system 164 and the charge former, e.g., the throttle body 182,generally do not generate or conduct much heat. The intake system 164and the charge former are generally protected from heat carried by theexhaust system 168 because the exhaust system 168 is positioned oppositeto the intake system 164 in the illustrated arrangement. Thus, theengine heat and the exhaust heat can be generally isolated from theintake system 164 during forward operation of the off-road vehicle 30.The temperature of the intake air, therefore, is not greatly affected bythe heat generated during operation of the off-road vehicle 30 andengine output efficiency can be kept in good condition. Along theselines, placement of a radiator preferably is generally below the airintake such that heat generated in the region of the radiator does notadversely affect engine performance through heating of the air inductedinto the engine.

Furthermore, in the illustrated intake system 164, the intake system 164generally does not extend along a heat generating or conducting surfaceof the engine 142. Thus, the engine heat is generally isolated from theintake system 164 in this arrangement. Also, the illustrated air cleaner188 is greatly spaced from the engine 142. As such, any air that isheated by the engine 142 and the exhaust system 168 will not be drawninto the air intake system 164, which improves the engine outputefficiency. Additionally, due to the elevated nature of the air inletand air cleaner 188, water also is very unlikely to be drawn into theintake system 164. Furthermore, because the air cleaner 188 ispositioned below the hood 134, water is unlikely to splash its way intothe air cleaner.

As illustrated, the exhaust conduits 208 extend along a relatively lowerportion of the off-road vehicle 30 in the illustrated arrangementbecause the exhaust conduits 208 are directed generally downward andrearward instead a wrapping around from a forward or lateral surface ofthe engine. The exhaust conduits 208, thus, are sufficiently spacedapart from the driver and/or the passenger. As a result, the seats 68can be positioned closer to the engine 142, which allows a narroweroverall construction for the vehicle or a closer mounting of the splitseats 68.

Although the present invention has been described in terms of a certainpreferred embodiment, other embodiments apparent to those of ordinaryskill in the art also are within the scope of this invention. Thus,various changes and modifications may be made without departing from thespirit and scope of the invention. The scope of the present invention isintended to be defined only by the claims that follow.

1. An off-road vehicle comprising a frame, a plurality of wheelssupporting the frame, at least two seat assemblies disposed side by sideon the frame, the seat assemblies being spaced apart from each other todefine a space therebetween, an internal combustion engine powering thewheels, at least a portion of at least one of the two seat assembliesoverlapping a portion of the engine as viewed from above, wherein theengine is disposed generally adjacent to the seat assemblies, the enginehaving a front surface generally facing the space with an intake portopening at the front surface.
 2. The off-road vehicle as set forth inclaim 1, wherein the engine has a portion positioned generally at a rearend of the space, the portion comprising the intake port.
 3. Theoff-road vehicle as set forth in claim 2, additionally comprising anintake system extending generally forwardly from the intake port.
 4. Theoff-road vehicle as set forth in claim 3, wherein the intake systemcomprises a throttle body, the throttle body comprising a throttlevalve, the throttle body being at least partially disposed within thespace.
 5. The off-road vehicle as set forth in claim 4, wherein theintake system comprises an air intake duct disposed upstream relative tothe throttle body, the intake duct generally extending forwardly fromthe throttle body and a forward portion of the intake duct extendingdownwardly.
 6. The off-road vehicle as set forth in claim 5 additionallycomprising a floorboard extending at least forwardly from a base portionof the seat assemblies, the intake duct further comprising a portionthat extends forwardly of the seat assemblies at a location generallybelow a portion of the floorboard.
 7. The off-road vehicle as set forthin claim 6, wherein the intake system comprises an air cleaner unit thatis connected to the intake duct.
 8. The off-road vehicle as set forth inclaim 7 additionally comprising a hood covering at least a forwardportion of the frame, the air cleaner unit being disposed below thehood.
 9. The off-road vehicle as set forth in claim 5, wherein the seatassemblies define a top surface and a forward surface, the intake ductextending generally along the top and forward surfaces.
 10. The off-roadvehicle as set forth in claim 6, wherein the floorboard comprises anupward projection that defines a tunnel, the intake duct extendingwithin at least a portion of the tunnel.
 11. The off-road vehicle as setforth in claim 5, wherein the intake duct comprises an accumulatordisposed between the throttle body and the balance of the intake duct,an inner diameter of the accumulator being greater than an innerdiameter of the balance of the intake duct.
 12. The off-road vehicle asset forth in claim 1, wherein the engine comprises an exhaust portcommunicating with the combustion chamber, the engine comprising a rearsurface and the exhaust port opening through the rear surface.
 13. Theoff-road vehicle as set forth in claim 12 additionally comprising anexhaust system, the exhaust system extending rearward from the exhaustport that opens through the rear surface.
 14. The off-road vehicle asset forth in claim 2, wherein the seat assemblies define a rear surface,at least a portion of the engine being disposed forward of the rearsurface.
 15. The off-road vehicle as set forth in claim 2, wherein theseat assemblies define a top surface, at least a portion of the enginebeing disposed lower than the top surface.
 16. The off-road vehicle asset forth in claim 15, wherein the seat assemblies define a rearsurface, at least a portion of the engine being disposed forward of therear surface.
 17. An off-road vehicle comprising a frame, a plurality ofwheels supporting the frame, at least two seat assemblies disposed sideby side on the frame, the seat assemblies being spaced apart from eachother to define a space therebetween, an internal combustion enginepowering the wheels, at least a portion of at least one of the two seatassemblies overlapping a portion of the engine as viewed from above,wherein each of the seat assemblies comprises a seat cushion, at least aportion of the internal combustion engine being positioned higher than abottom of the seat cushion.
 18. An off-road vehicle comprising a frame,a plurality of wheels supporting the frame, at least two seat assembliesdisposed side by side on the frame, the seat assemblies being spacedapart from each other to define a space therebetween, and an internalcombustion engine powering at least one of the plurality of wheels, atleast one of the two seat assemblies overlapping a portion of the engineas viewed from above, wherein each of the seat assemblies comprises aseat cushion, at least a portion of the internal combustion engine beingpositioned higher than a bottom of the seat cushion.